Course of ship circling lake (6)
I believe the answer is:
series
'course' is the definition.
(I've seen this before)
'ship circling lake' is the wordplay.
'ship' becomes 'ss'.
'circling' indicates putting letters inside (circling can mean going around or containing).
'lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes'**).
'ss' enclosing 'erie' is 'SERIES'.
'of' is the link.
(Other definitions for series that I've seen before include "Number of related things coming one after another" , "Sequence; tone row" , "Sequence of programmes etc." , "Set of episodes" , "Set of TV programmes" .)